Patent GB-734131-A (GB)
Title: Process of making vinylidene chloride and vinyl chloride
IPC: C07C17/00
Filed: 1952-11-13
Abstract: Vinylidene chloride and vinyl chloride are obtained by adding chlorine and an inert diluent gas or vapour in the absence of a catalyst to a hydrocarbon gas consisting of ethane or a mixture of ethane and ethylene containing more than 50 per cent by volume of ethane, the mol. ratio of chlorine to hydrocarbon being in accordance with the formula mols. Cl2=x mols. C2H6+(x - 1) mols. C2H4 in which x has a value from 1.9 to 3.0 and the volume of the diluent is sufficient to control the subsequent reaction temperature within the prescribed limits under the reaction conditions, passing the gaseous mixture through a reaction zone maintained at 450-600 DEG  C. at a flow rate such as to ensure that the gases remain in the said zone for an average time of at least 0.5 second, and separating the vinylidene chloride and vinyl chloride from the reaction product. Examples of suitable diluents are nitrogen, steam, hydrogen chloride, carbon tetrachloride and perchlorethylene.  The preferred diluent is hydrogen chloride which is formed in the reaction and can be separated from the reaction products and recycled in the amount required to maintain the desired temperature.  Preferred conditions of operation are a Cl2 : C2H6 ratio of between 2.3 and 2.7, a temperature between 500 DEG  and 550 DEG  C. and a residence time of 1 to 1.5 seconds. Both ethylidene chloride and methyl chloroform, which are formed as by-products, may be separated from the reaction product and recycled to increase the yield of vinylidene chloride, the proportion of Cl2 in the feed being reduced by 2 mols. for every mol. of ethylidene chloride that is recycled and being reduced by 3 mols. for every mol. of methyl chloroform recycled. Small amounts of tetrachloroethanes and of trichloroethylene are also formed in the reaction.  Ethylene is also formed and, if desired, may be recycled to the reaction zone.  In examples: (1) ethane, chlorine and steam are premixed and passed into a reactor in which the maximum temperature is maintained at about 540 DEG  C., the average residence time of the gases in the reactor being about 2 seconds.  The reactor exit gases are scrubbed with water to remove HCl and steam and the liquefiable chlorinated compounds condensed and distilled to yield vinyl chloride and vinylidene chloride and a small amount of cis- and trans-1,2-dichloroethylenes; (2) a series of runs is made in which ethane, chlorine and steam are mixed and passed into the reactor at varying flow rates in mols. per hour, the reaction being operated at varying reactor temperatures and residence times.  Tabulated results are given to show the yields of products obtained under various operating conditions; (3) to show the effect of mixing ethylene with ethane in the feed two series of runs are made under comparable conditions, in one series (3 runs) with ethane alone a Cl2 : C2H6 ratio of 2.7 is used and in the other series a mixture of 2 parts ethane to 1 part of ethylene is used, the volume of chlorine being equivalent to that in the first series as calculated from the above equation. Steam is used as diluent in each case and the average residence time is 2.7 seconds and the reactor temperature is 530 DEG C. Tabulated results are given which show that the inclusion of the stated amount of ethylene in the feed increases the amount of vinyl chloride and higher boiling compounds at the expense of vinylidene chloride.  The hydrocarbons used may be obtained from petroleum refinery gases from which a commercial ethane fraction which usually contains ethylene can be separated.